In the formation of extrusion dies for making honeycomb structures, the outlet face may be formed with a plurality of saw cuts such as disclosed in U.S. Pat. No. 3,790,654, where the cell pattern to be formed includes continuous linear walls extending transversely across the honeycomb structure, such as when forming honeycomb structures with square, rectangular or triangular cell shapes. However, when the desired cell configuration includes shapes wherein the bounding walls of the cells do not linearly extend transversely across the honeycomb structure, such as the brickwork shape of FIG. 4 and the T-shape of FIG. 8 of U.S. Pat. No. 3,899,326, methods other than saw cuts must be utilized to form the cell pattern. Such methods may include the incorporation of a plurality of individual cores or pins which are manually positioned on a die body and bolted thereto as shown in U.S. Pat. No. 2,908,037, or the die may be formed of a plurality of laminated etched sheets of photosensitive glass or glass-ceramic materials as disclosed in U.S. Pat. No. 3,846,197. However, the use of individually positioned core pins which are bolted to a die body not only requires the precise drilling and tapping of each individual hole for applying the core pins, but is also costly and time consuming to manufacture. Further, the use of laminated etched photosensitive glass and glass-ceramic materials for forming a die is also not only expensive and time consuming to manufacture, but is not particularly durable when extruding abrasive or viscous materials.
Accordingly, the present invention has overcome the problem of forming an extrusion die for making honeycomb structures by initially utilizing a conventional saw-cut die and selectively positioning a plurality of tab members in certain portions of the discharge slots of such die so as to convert the cellular structure originally produced thereby into that of a different desired structure.